The invention provides a tobacco leaf cultivation method for improving a tobacco leaf grade structure. The method is implemented during the tobacco plant field growth stage. For burley tobacco or Maryland tobacco, during the vigorous growing stage of tobacco plants, namely, about 35 days after transplantation, blades of three tobacco leaves are picked off continuously in good time; for the flue-cured tobacco, during the spherical plant stage of tobacco plant growth, namely, about 28 days after transplantation, three tobacco leaves are picked off continuously, and later production technology measures and modulation technology measures are executed according to the current scheme. By the application of the technical method, the photosynthetic environment of the tobacco plants can be remarkably improved, the high middle tobacco rate in a raw material of the modulated tobacco is increased, the tobacco leaf yield is increased, the tobacco leaf quality level is improved, and therefore the target of improving the tobacco leaf grade structure is achieved.